Please find a wonderful interview with Sam Kim, Director of product development of HP's calculator group:
http://www.videsignline.com/GLOBAL/electronics/designline/shared/article/showArticle.jhtml?articleId=206102182&pgno=1
Some of the statements:
The 8502 is designed by Sunplus Technology, a Taiwanese company. It's based on the 6502, an 8-bit processor that first appeared on the Commodore 64...
The firmware also resides on the 8502 microcontroller. That leaves almost the entire flash memory available for user programming. The 32-kbyte flash leaves about 30 kbytes available to the end user, enough for about 20,000 lines of code.
The initial specifications for the 35s came from a team within HP. Once that spec was agreed upon, the design was outsourced to a team in Taiwan. But even after it was sent overseas, the HP internal design team continued to work on other aspects of the 35s, in parallel with the external team in Taiwan. The internal HP team actually resided in four separate locales: Boise, Cupertino, San Diego, and Vancouver.
Enjoy!
Regards,
Joerg